Let's think about this with common sense.  QB is designed for small, medium, and medium to large businesses.  With the said, the 4500 cap on statements is ridiculous.  QB does not allow you to delete old and/or customers that have any kind of activity.  A business can easily hit the 4500-mark whatever size they are. 

Keeping QB running smoothly and using a 4500 max statement seems like a task that can be achieved.  Yes, it will take time, but there are competent computer experts that can tackle this issue. Customers complaining (many of us) should be enough to have this changed.